Optimized cvsexportcommit: calling 'cvs status' once instead of once per touched...

Optimized cvsexportcommit: calling 'cvs status' once instead of once per touched file.

Runtime is now independent of the number of modified files.

The old implementation executed 'cvs status' for each file touched by the patch
to be applied. The new code calls 'cvs status' only once with all touched files
and parses cvs's output to collect all available status information.

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>